This invention relates to the use of selected additives in alkanol fuels to reduce or inhibit wear.
The use of alcohols and particularly methanol as an engine fuel has been known for some time. However, the use of methanol and other such alkanol fuels, particularly when used neat, has been found to produce excessive wear. Much of the wear which is caused by a fuel of this type, such as methanol, has been found to take place on the piston rings and upper cylinder areas of an engine. This wear results from "washing away" the lubricant film and direct chemical attack of the fuel and its corrosive combustion products on the metal surfaces of the cylinder liner. Fuel blowby into the lubricant, i.e. the fuel and its combustion products blow past the rings, and the resulting reaction with lubricant additives also can lead to a general increase in engine wear with alkanol fuels.
Changes in lubricant formulations have been one approach to solving the aforesaid wear problem associated with alkanol fuels. Other attempts have included the use of additives in methanol fuel to help lubricity, while reducing the wear characteristics. Additives used have included fatty alcohols, alcohol ethoxylates, fatty acids and ethoxylates, ester including mono-, di, polyol and phosphate esters and polyalkylene glycols as disclosed in U.S. Pat. No. 4,375,360. Other additives have included a number of organo acids as shown in U.S. Pat. Nos. 4,177,768; 4,185,594; 4,242,099; and 4,248,182. Further additives noted as useful in alkanol fuels have included n-hydroxy hydrocarbonamide disclosed in U.S. Pat. No. 4,198,931; fatty acid amides or esters of diethanolamine disclosed in U.S. Pat. No. 4,204,481; and straight chain aliphatic primary amines disclosed in U.S. Pat. No. 4,208,190.
While a number of different approaches have been disclosed, as described above, to provide reduced wear in alkanol fueled engines, there is further need for a fuel system which will provide reduced engine wear and improved lubricity while retaining compatibility.